Welder generator electrode based engine speed control

ABSTRACT

A welding system includes an engine-driven welder generator that produces welding power. A welding torch receives the welding power and applies it to a stick electrode to initiate and maintain a welding arc. A parameter of the welding power, such as voltage, is monitored, such as to determine whether spikes occur during a short time after arc initiation. Based upon the monitored parameter, the engine speed is controlled. The engine speed may be increased or maintained at an elevated level if the monitored parameter indicates that particular types of electrode are being used, such as XX10 or cellulose electrodes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of U.S. Non-Provisionalpatent application Ser. No. 13/910,033, entitled “Welder GeneratorElectrode Based Engine Speed Control”, filed Jun. 4, 2013, which is aNon provisional application of U.S. Provisional Patent Application No.61/676,615, entitled “Welder Generator Electrode Based Engine SpeedControl”, filed Jul. 27, 2012, both of which are hereby incorporated byreference in their entireties.

BACKGROUND

The present invention relates generally to the field of welding systems,and more particularly to systems designed for stick weldingapplications.

Many welding systems have been developed for providing power and otherconsumables for joining workpieces. In certain applications, weldingprocesses may be based upon the use of so-called stick electrodes thattypically comprise a metal rod made of a desired material formulation,and a flux coating that facilitates metal transfer, promotes properformation of the weld bead, shields the fresh weld bead, and so forth.Depending upon the type and size of the electrode, the desired arcbetween the electrode and the workpiece may be difficult to start and/ormaintain. Special processes have been developed to accommodate differentelectrodes.

However, further improvement is needed. In particular, improvements areneeded that permit the use of specific power regimes based uponperformance of particular welding electrodes.

BRIEF DESCRIPTION

The present invention provides a novel approach to welding power supplycontrol designed to respond to such needs. In accordance with certainembodiments, a welding method comprises initiating a welding arc betweena stick electrode and a workpiece based upon power provided by anengine-driven welder generator, and monitoring an electrical parameterof power provided to the stick electrode. Engine speed is thencontrolled based upon the monitored electrical parameter. The electricalparameter may be welding arc voltage, and the engine speed may beincreased or maintained at an elevated level if a certain number ofvoltage spikes occurs within a preset time after arc initiation.

In accordance with another aspect, the invention provides a weldingmethod that comprises initiating a welding arc between a stick electrodeand a workpiece based upon power provided by an engine-driven weldergenerator, monitoring an electrical parameter of power provided to thestick electrode, and, based upon the monitored electrical parameter,determining a type of stick electrode employed. The engine speed is thencontrolled based upon the determined type of stick electrode.

In accordance with a further aspect, the invention provides a weldingsystem comprising an engine-driven welder generator comprising an enginethat drives a generator to produce welding power. A welding torch isconfigured to receive the welding power, to support a stick electrode,and to apply the welding power to the stick electrode to establish andmaintain a welding arc. A sensor is configured to sense an electricalparameter of the welding power applied to the electrode. Controlcircuitry is configured to receive signals from the sensor, to determinea type of stick electrode employed, and to control engine speed basedupon the determined type of stick electrode employed.

DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a diagrammatical representation of an exemplary applicationfor power conversion circuitry, in the form of a welding system;

FIG. 2 is a circuit diagram for a portion of the power conversioncircuitry of FIG. 1, particularly illustrating certain functionalcircuit components;

FIG. 3 is a perspective view of an exemplary power conversion module inaccordance with aspects of the system shown in FIG. 1;

FIG. 4 is an exploded view of certain of the components of the module ofFIG. 3;

FIG. 5 is a partial perspective view of the same module with an upperenclosure element removed to reveal internal circuit components;

FIG. 6 is an exploded view of an exemplary rectifier module inaccordance with aspects of the present disclosure;

FIG. 7 is a perspective view of the same module from a back side;

FIGS. 8A and 8B are flow charts illustrating exemplary logic forcontrolling the speed of an engine generator set in a weldingapplication;

FIGS. 9A and 9B are similar flow charts illustrating logic for speedcontrol of an engine generator; and

FIGS. 10A and 10B are similar flow charts illustrating logic for enginespeed control for another exemplary application.

DETAILED DESCRIPTION

Turning now to the drawings, and referring first to FIG. 1, an exemplarywelding system 10 is illustrated that includes a power supply 12 forproviding power for welding, plasma cutting and similar applications.The power supply 12 in the illustrated embodiment comprises an enginegenerator set 14 that itself includes an internal combustion engine 16and a generator 18. The engine 16 may be of any suitable type, such asgasoline engines or diesel engines, and will generally be of a sizeappropriate for the power output anticipated for the application. Theengine will be particularly sized to drive the generator 18 to produceone or more forms of output power. In the contemplated application, thegenerator 18 is wound for producing multiple types of output power, suchas welding power, as well as auxiliary power for lights, power tools,and so forth, and these may take the form of both AC and DC outputs.Various support components and systems of the engine and generator arenot illustrated specifically in FIG. 1, but these will typically includebatteries, battery chargers, fuel and exhaust systems, and so forth.

Power conditioning circuitry 20 is coupled to the generator 18 toreceive power generated during operation and to convert the power to aform desired for a load or application. In the illustrated embodimentgenerator 18 produces three-phase power that is applied to the powerconditioning circuitry 20. In certain embodiments, however, thegenerator may produce single phase power. The power conditioningcircuitry includes components which receive the incoming power,converted to a DC form, and further filter and convert the power to thedesired output form. More will be said about the power conditioningcircuitry 20 in the discussion below.

The engine 16, the generator 18 and the power conditioning circuitry 20are all coupled to control circuitry, illustrated generally by referencenumeral 22. In practice, the control circuitry 22 may comprise one ormore actual circuits, as well as firmware and software configured tomonitor operation of the engine, the generator and the powerconditioning circuitry, as well as certain loads in specificapplications. Portions of the control circuitry may be centrally locatedas illustrated, or the circuitry may be divided to control the engine,generator and power conditioning circuitry separately. In mostapplications, however, such separated control circuits may communicatewith one another in some form to coordinate control of these systemcomponents. The control circuitry 22 is coupled to an operator interface24. In most applications, the operator interface will include asurface-mounted control panel that allows a system operator to controlaspects of the operation and output, and to monitor or read parametersof the system operation. In a welding application, for example, theoperator interface may allow the operator to select various weldingprocesses, current and voltage levels, as well as specific regimes forwelding operations. These are communicated to a control circuitry, whichitself comprises one or more processors and support memory. Based uponthe operator selections, then, the control circuitry will implementparticular control regimes stored in the memory via the processors. Suchmemory may also store temporary parameters during operation, such as forfacilitating feedback control.

Also illustrated in FIG. 1 for the welding application is an optionalwire feeder 26. As will be appreciated by those skilled in the art, suchwire feeders are typically used in gas metal arc welding (GMAW)processes, commonly referred to as metal inert gas (MIG) processes. Insuch processes a wire electrode is fed from the wire feeder, along withwelding power and, where suitable, shielding gas, to a welding torch 28.In other applications, however, the wire feeder may not be required,such as for processes commonly referred to as tungsten inert gas (TIG)and stick welding. In all of these processes, however, at some point andelectrode 30 is used to complete a circuit through a workpiece 32 and awork clamp 34. The electrode thus serves to establish and maintain anelectric arc with the workpiece that aides in melting the workpiece andsome processes the electrode, to complete the desired weld.

To allow for feedback control, the system is commonly equipped with anumber of sensors which provide signals to the control circuitry duringoperation. Certain sensors are illustrated schematically in FIG. 1,including engine sensors 36, generator sensors 38, power conditioningcircuitry sensors 40, and application sensors 42. As will be appreciatedby those skilled in the art, in practice, a wide variety of such sensorsmay be employed. For example, engine sensors 36 will typically includespeed sensors, temperature sensors, throttle sensors, and so forth. Thegenerator sensors 38 will commonly include voltage and current sensors,as will the power conditioning circuitry sensors 40. The applicationsensors 42 will also typically include at least one of current andvoltage sensing capabilities, to detect the application of power to theload.

FIG. 2 illustrates electrical circuitry that may be included in thepower conditioning circuitry 20 illustrated in FIG. 1. As shown in FIG.2, this circuitry may include the generator windings 44, illustratedhere as arranged in a delta configuration, that output three-phase powerto a rectifier 46. In the illustrated embodiment the three-phaserectifier is a passive rectifier comprising a series of diodes thatprovide a DC waveform to a DC bus 48. Power on the DC bus is thenapplied to filtering and conditioning circuitry 50 which aide insmoothing the waveform, avoiding excessive perturbations to the DCwaveform, and so forth. The DC power is ultimately applied to a switchmodule 52, which in practice comprises a series of switches andassociated electronic components, such as diodes. In weldingapplications, particular control regimes may allow for producing pulsedoutput, AC output, DC output, and particularly adapted regimes suitablefor specific processes. As will be appreciated by those skilled in theart, various switch module designs may be employed, and these may useavailable components, such as insulated gate bipolar transistors(IGBTs), silicon controlled rectifiers (SCRs), transformers, and soforth. Many of these will be available in packaging that includes boththe switches and/or diodes in appropriate configurations.

Finally, an output inductor 54 is typically used for weldingapplications. As will be appreciated by those skilled in the weldingarts, the size and energy storage capacity of the output inductor isselected to suit the output power (voltage and current) of theanticipated application. Although not illustrated, it should also benoted that certain other circuitry may be provided in this arrangement,and power may be drawn and conditioned in other forms.

While only certain features of the exemplary systems have beenillustrated and described herein, many modifications and changes willoccur to those skilled in the art. For example, in addition to theoutput terminals illustrated in FIG. 2, power may be drawn from the DCbus for use in other conversion processes. This may allow for DCwelding, for example, as well as for the supply of synthetic AC powerfor various auxiliary applications. The synthetic auxiliary power may beadapted, for example, for single phase power tools, lighting, and soforth. Where provided, such power may be output via separate terminals,or even conventional receptacles similar to those used for power griddistribution.

Various physical arrangements may be envisaged for packaging some or allof the circuitry discussed above. A presently contemplated arrangementis illustrated in FIG. 3. FIG. 3 shows an integrated power module 56that incorporates essentially the rectifier circuitry of FIG. 2, thefiltering and conditioning circuitry, as well as the switch modules. Asdiscussed below, the integrated power module 56 also includes at least adrive board for the switches. Various bus structures are also includedin the package as discussed below. The integrated power module 56 isillustrated as including an upper housing 58 and a lower housing 60.These may be made of non-conductive or insulative materials, such asinjection molded plastic. The illustrated housings facilitate coveringthe components, supporting them mechanically, and also separating themas needed for electrical insulation purposes. Shown in FIG. 3 are inputterminals 62 which lead into rectifier modules 64 discussed below. Eachof these input terminals will be coupled to an output phase of thegenerator in a three-phase application.

FIG. 4 shows an exploded view of the exemplary module illustrated inFIG. 3. As mentioned above, the module 56 includes and upper housing 58and a lower housing 60 with the various circuit components disposed inthese housing sections and mechanically supported by the housing. In theillustration of FIG. 4, a pair of rectifier clamp bars 66 are shown thatcoupled to output of diodes within the rectifier modules as describedmore fully below. These clamp bars are conductive, and apply power to anupper bus plate 68. Bus plate 68 forms one side of the DC bus discussedabove with reference to FIG. 2. A lower bus plate 72 is also illustratedand will make contact with diodes of the rectifier modules 64 to formthe lower branch of the DC bus. An insulator plate is positioned betweenlower bus plate 72 and upper bus plate 68 for maintaining voltagepotential between the plates. An output bus bar 70 is provided forchanneling output power from the power module. Capacitors 74 are shownexploded from the lower housing 60. In the illustrated embodiment thelower housing 60 comprises apertures and structures designed to receivethese capacitors, to mechanically support them, and to allow them to becoupled to the bus bar plates. The switch modules are comprised in asubassembly, in this case a buck converter module 76. The buck convertermodule is also secured to the lower housing, and supports a driver boardfor applying drive signals to the switches of the buck converter module.The buck converter module is in contact with the upper and lower busplates when the integrated power module is assembled, as well as withthe output bar 70. Finally, an output resistor 78 is provided that willextend between terminals external to the housing in the currentlycontemplated embodiment.

FIG. 5 is an illustration of the same module, from a differentperspective and with the upper housing removed to show theinterconnection of various components. Here the module 56 can be seen ascomprising the lower housing with the rectifier modules 64 at an inputend of the structure. The rectifier clamp bar 66 is in contact withupper diodes forming the rectifier. The upper bus plate 68 is alsovisible and is in contact with this same side of the rectifier modulesand with the output terminal. The capacitors, one of which is visible inFIG. 5, are electrically and mechanically secured to both the upper busplate 68 and to the lower bus plate 72, corners of which are visible incorner cut-outs of the upper bus plates. A driver circuit board 80 isshown in FIG. 5. As will be appreciated by those skilled in the art, thedriver circuit board is populated with electronic circuitry that allowsfor application of drive signals to the power electronic switches of thebuck converter module. These drive signals will typically be generatedbased upon control signals from the one or more processors within thecontrol circuitry discussed above. As also shown in FIG. 5, conforminghousing sections 82 may be defined for receiving and securely holdingvarious components, such as the capacitors 74 in this case. Moreover,one or more of the circuits may be designed with fins to assist in airor forced cooling. Such fins 84 illustrated for the buck convertermodule shown in FIG. 4.

It has been found that the particular arrangements of the packagingshown in the figures is well suited to compact and efficient design,manufacturing, assembly and operation. In the illustrated embodiment,the circuit components may be formed in advance and sub-assemblies made,particularly of the converter module and the rectifier modules, as wellas the drive circuit board. These are then simply assembled in thepackage as described. The resulting package is space and energyefficient, and allows for cooling of the power electronic devices duringoperation. The package may be used in wide range of applications and isparticularly well-suited to the presently contemplated welding andplasma cutting applications, based upon inputs from a welder generatorwhich is, together with the integrated power module, positioned in amobile enclosure.

FIGS. 6 and 7 illustrate a presently contemplated design for therectifier modules that is useful in allowing them to be easilyintegrated into the power module. As shown in FIG. 6, for example, eachrectifier module comprises a housing 86 which is made of an injectionmolded conductive material, such as aluminum or an aluminum alloy. Thehousing includes multiple integral features that are formed in themolding process. Ideally, little or no further machining is requiredfollowing molding. The housing includes an integral terminal extension88 to which an input conductor is coupled during assembly of theintegrated power module into the welder generator. The body 90 of thehousing 86 is unitary such that the entire body is placed at thepotential applied to the terminal extension 88. Thus, when used inapplications as a portion of a rectifier of AC input power, therectifier module body will typically receive an AC waveform that isapplied to the entire body during operation. The body comprises finextensions 92 on rear side thereof to aid in cooling of the body and theentire module. Recesses 94 are formed in opposite face of the body andreceive diode modules 96. In the illustrated embodiment for such diodemodules are received, although it should be noted that the four diodemodules function in the circuitry as only two diodes. That is, the uppertwo diode modules illustrated in the figures function as the upper diodein the rectifier circuitry of FIG. 2 (for one of the phases) while thelower pair of diodes function as the lower diode (for the same phase).Each diode module comprises a conductive body 98 within which the diodeitself is formed. This conductive body forms the input side of eachindividual diode module, which is placed at the input potential when thediode modules are received within the recesses 94 of the body 90. Outputconductors 100 of each module extend from a center of the prospectivediode module. Electrical connection is made with these output conductors(which are sandwiched between the rectifier clamp bars discussed above).FIG. 7 illustrates the same diode module from a rear side. Here the fins92 can be seen extending from the body 90, as well as the input terminalextension 88. The bodies 98 of the individual diode modules 96 areillustrated before they are pressed into the recesses 94 of the body.

It has been found that the foregoing design allows for a highlyefficient manufacturing process, simple assembly, and robustperformance. In particular, with each rectifier module body being placedat the input potential, multiple phases of the rectifier can beseparated from one another by the non-conductive material of the housing(see, e.g., FIG. 5). It should also be noted that the flangedarrangements of the module body and the tongue-in-groove mounting allowfor environmental isolation of the modules and diodes, which may beparticularly important in mobile applications in which the circuitry maybe subjected to weather and environmental factors, even when placed in aunit enclosure. In practice, one or multiple phases can be rectified inthis manner. Moreover, it should be noted that while pairs of diodes areutilized to perform the function of individual diodes illustrateddiagrammatically in FIG. 2, in practice, one, two or more such diodesmay perform this function. Thus, the body of the rectifier module may bere-configured and the recesses reduced or multiplied, and their positionchanged to accommodate the particular packaging envisaged.

The circuitry and systems described above may be controlled in variousmanners, depending upon the particular application or load. In the caseof a welder driven by an engine generator set, it is presentlycontemplated that control may be made to the speed of the engine inorder to optimize output of the generator and power conditioningcircuitry. This optimization will typically allow for reduced speedswhen appropriate for providing power to the welding load, with increasedspeeds where additional voltage and/or power are required. This allowsfor reduced fuel usage, noise and exhausts where lower power and/orvoltage requirements are demanded, while nevertheless accommodatinghigher requirements within the capabilities of the system. FIGS. 8, 9and 10 illustrate exemplary logic for carrying out this type of control.

The control logic summarized in FIGS. 8A and 8A is particularly directedto decisions and control logics for stick welding applications. Theexemplary logic, designated globally by reference numeral 102 begins atstep 104 where an initial engine speed is adopted. In particular,engines presently contemplated will have a power and voltage curve thatprovide for higher output power and voltage as speed increases. Thenominal initial speed of 2400 RPM can be regulated by feedback controlof the engine speed and throttle positions (and any other desiredcontrolled variables), typically implemented by an engine electronicgovernor or control circuitry of the type described above. As indicatedby reference numeral 106, then, a process or mode will typically beselected by the operator. That is, the operator may, in a presentlycontemplated embodiment, enter a stick process, utilizing low hydrogenelectrodes as indicated at reference numeral 108, or a celluloseelectrode process as indicated at reference numeral 110. Moreover,synthetic auxiliary power may be generated by the system and output asindicated by reference numeral 112. The selection of the XX18 (lowhydrogen) or XX10 (cellulose) mode will typically be made by theoperator interface described above. The detection of synthetic auxiliarypower output may be detected by a current sensor on an auxiliary powerline of the power conditioning circuitry.

Based upon the mode, then, the system may detect a pre-set current forthe welding output. As illustrated in FIG. 8A, this current may fallwithin various ranges, such as below 158 AMPS, above 260 AMPS, or atvarious ranges between. The current will typically be set via theoperator interface. Based upon this current setting, then, the controlcircuitry causes the engine to accelerate to desired engine speed,again, adapted based upon the voltage and/or power curve of the engine.In the illustrated embodiment, the new speed indicated by referencenumeral 116 will be either 2800 RPM, 3200 RPM, or 3600 RPM.

Thereafter, the algorithm will call for either a power calculation or apower and voltage calculation. Specifically, in a stick mode, in theillustrated embodiment, the system will sense current and voltage of theoutput waveform and calculate output power of the welding output basedupon these measured parameters. Similarly, if synthetic power is outputfor auxiliary application, the auxiliary draw may be added to thiswelding power output to obtain the calculations indicated at referencenumeral 118.

The logic summarized in FIGS. 8A and 8B also allow for determination ofcertain electrode types that may be used in stick welding, an adaptationof the engine and generator output performance based upon the electrodetype. In particular, at step 118, if the system is operating in pipemode, the logic may determine whether a certain type of electrode, inthis case an electrode recognized in the art as “XX10” is identified bymonitoring voltage spikes during initial welding operations. Suchelectrodes may be termed “cellulose” electrodes. To operate effectivelysuch electrodes should be powered with sufficient voltage to ridethrough high voltage requirements unique to these electrodeformulations. The voltage will not be constant, but a transient may berepeated and is detectable by monitoring the arc voltage. If the voltagerequirement is not met, the arc may be unstable, and may intermittentlybe extinguished. While heretofore known power sources addressed suchrequirements by raising the voltage potential as high as possible andsometimes beyond during a weld, or using inductors or stabilizers inseries with the output, the present approach uses an adaptive technique.This adaptive technique, like the other speed increase approachessummarized, allows for running the engine as slow as possible to save onnoise and fuel. The available voltage changes with engine speed andtherefore the system will seek a speed just sufficient to stabilize thearc. In a presently contemplated embodiment, for example, when usingXX10 electrodes, transients will be noted during the initial moments ofwelding. In this contemplated embodiment, if there are more than 5(e.g., 10) such transients above a threshold (e.g., 44 volts) in thefirst second of welding, control moves the engine speed to the speedrequired as summarized in FIG. 8A.

Still more specifically, the control solution for this type of electrodeallows for initiating and controlling the arc start, then monitoring forhigh voltage events once the arc is established. In one presentlycontemplated approach, if there are 10 such events, the engine speed israised incrementally by increments of 400 RPM above the initialoperating point. With cellulose electrodes, these events will beexpected to happen quickly, and the engine speed change will generallybe unnoticed. If the operator runs a different type of electrode butpulls the arc, the engine speed may also respond in a similar manner.This could be somewhat more noticeable, but would nevertheless providesmooth operation of the electrode. The control technique monitors thevoltage of the output of the machine, which generally represents the arcvoltage. In the presently contemplated embodiment, the voltage ismonitored rapidly (e.g., every 100 uS). The system determines if thevoltage events over the threshold represent the likely use of acellulose electrode, and thus adapts for the electrode requirements. Thehigher engine speed will increase the bus voltage, and thereby thevoltage output.

As indicated at reference numeral 120 in FIGS. 8A and 8B, then, basedupon the power calculation or power/voltage calculation at step 118, thesystem may remain at the current speed, or may increase in speed asrequired. Thereafter, similar calculations are made at step 122, andfurther boosts in engine speed and output are made, where appropriate,at step 124. At step 126 further similar calculations are made, todetermine whether a final boost may be made to the final engine speed.

Several notes of interest should be made with reference to the logicsummarized in 8A and 8B. First, once the arc is initiated for welding,the system may boost output to higher levels, but generally does notreturn to the initial speed until the arc is extinguished (i.e., aftertermination of a current weld). Moreover, once at a boosted speed, thesystem may remain at that speed or increase incrementally to higherspeeds as required. Moreover, the increments in the presentlycontemplated design are of 400 RPM from the initial speed of 2400 RPM toa final speed of 3600 RPM. These increments could be of differentmagnitudes, of a different number, and could have different beginningand ending points, depending upon the engine specifications, thegenerator specifications, the number of steps desired, and so forth. Ingeneral, these steps will be contemplated based upon the overall enginepower and voltage curves. Finally, while the power calculations asopposed to the power/voltage calculations are indicated for particularwelding processes, similar calculations may be made independent of theparticular selected process, particularly where certain types ofelectrodes with different anticipated performance may be employed.

FIGS. 9A and 9B illustrate similar control logic, here for TIG weldingapplications. As indicated in FIG. 9A, this TIG control logic,designated generally be reference numeral 132 begins with an initialrunning condition of 2400 RPM as indicated at step 134. The user mayselect a TIG or pulse TIG process as indicated at step 136, such as viathe power supply interface. Here again, synthetic auxiliary power outputmay be detected as indicated at step 112. At step 138, then, the systemdetects a preset current value within a desired range, as describedabove in the case of the stick welding logic. Based upon the selectedprocess and the selected current, then, the engine may be caused to stayat the same speed or to increase speeds as indicated by referencenumeral 140. As indicated by reference 142, then, a power calculation ismade based upon detected current and voltage of the weld, and anyauxiliary power draw may be added to this calculation ad indicated byreference numeral 154. As shown in FIG. 9B, then, at step 144 the systemmay determine to stay at the initial speed or current speed or toadvance further to a higher speed. Similar power calculations are made,then, at step 146 and 150, resulting in decisions at steps 148 and 152.Here again, the beginning and end points for the speed range could bealtered, as may the particular incremental increases based upon thepower calculations. It may also be noted that, as in the case of stickwelding, the logic summarized in FIGS. 9A and 9B generally do not allowfor return to the initial engine speed until the arc is extinguishedfollowing the end of a particular weld.

FIGS. 10A and 10B illustrate similar logic for MIG welding. This logic,designated generally by reference numeral 156, begins with an initialengine running speed at step 158. The operator may select betweendifferent MIG welding processes, such as a solid wire process asindicated by reference numeral 160 or a flux core process as indicatedby reference numeral 162. Here again, synthetic auxiliary power may beprovided as indicated at block 112. In the embodiment illustrated, theinitial engine speed for use with solid wire is 3200 RPM, and for fluxcored wire, 3600 RPM, as indicated at steps 164. For flux cored wire,this speed is held initially for 3 to 5 seconds before allowing adown-correction (as indicated at step 168). For solid wire, the initialspeed is held approximately 1 second.

Subsequently, then, once the welding arc has started, a determinationmay be made whether to decrease the engine speed based upon a powercalculation, as indicated by reference numeral 166, which may includeaddition of any auxiliary power draw as indicated at reference numeral178. Based upon the calculation, the speed may be decreased andmaintained or further altered. It should be noted that in thisalgorithm, the initial speed may be maintained if the load requireshigher output, as indicated by the lines extending from step 164 to step174 (see FIG. 10B). If a speed reduction is possible (based on reducedpower requirements) the decrease may be implemented as indicated at step168. Further calculations are then made at steps 170 and 174, which maybe followed by decisions to increase speed as indicated at steps 172 and176. Here again, once speed has increased during a particular weld,speeds are not generally decreased until that weld has terminated.Moreover, as in the logic for stick and TIG welding, the particularbeginning and ending points of speed control, and the particularintervals or steps in speed may be adapted for different engines,generators and power conditioning circuitry.

The invention claimed is:
 1. A welding method comprising: initiating awelding arc between a stick electrode and a workpiece based upon powerprovided by a welding power supply unit; monitoring voltage and currentof welding power provided to the stick electrode to determine a type ofstick electrode employed based on transients of the welding powerrelative to a threshold; and increasing an engine speed of an engine ofthe welding power supply unit to an elevated level or maintaining theengine speed at an initial level, lower than the elevated level, basedat least in part upon the determined type of the stick electrodeemployed.
 2. The welding method of claim 1, wherein the engine speed isincreased to the elevated level if the stick electrode employed is anXX10 electrode.
 3. The welding method of claim 1, wherein the enginespeed is increased to the elevated level if the stick electrode employedis a cellulose electrode.
 4. The welding method of claim 1, wherein theengine speed is increased to the elevated level if a predeterminedvoltage profile is detected within a predetermined time after initiationof the welding arc.
 5. The welding method of claim 4, wherein the enginespeed is increased to the elevated level if the predetermined voltageprofile is detected within the first second following initiation of thewelding arc.
 6. A welding method comprising: initiating a welding arcbetween a stick electrode and a workpiece based upon power provided byan engine-driven welder generator; monitoring at least one electricalparameter of welding power provided to the stick electrode; based ontransients of the at least one electrical parameter relative to athreshold, determining a type of stick electrode employed; andincreasing an engine speed of an engine of the engine-driven weldergenerator to an elevated level or maintaining the engine speed at aninitial level, lower than the elevated level, based at least in partupon the determined type of the stick electrode employed.
 7. The weldingmethod of claim 6, wherein the at least one electrical parameter isvoltage of the welding power, current of the welding power, the weldingpower, or some combination thereof.
 8. The welding method of claim 7,wherein the at least one electrical parameter comprises the voltage ofthe welding power and the current of the welding power.
 9. The weldingmethod of claim 6, wherein the engine speed is increased to the elevatedlevel if the stick electrode employed is an XX10 electrode.
 10. Thewelding method of claim 6, wherein the engine speed is increased to theelevated level if the stick electrode employed is a cellulose electrode.11. The welding method of claim 6, wherein the engine speed is increasedto the elevated level if the stick electrode employed is identified as aparticular type of stick electrode.
 12. The welding method of claim 11,wherein the engine speed is increased to the elevated level if apredetermined voltage profile is detected within a predetermined timeafter initiation of the welding arc.
 13. A welding system comprising: awelding power supply unit configured to generate welding power; awelding torch configured to receive the welding power and to apply thewelding power to a stick electrode to establish and maintain a weldingarc; and a sensor configured to sense an electrical parameter of thewelding power applied to the stick electrode; and control circuitryconfigured to receive signals from the sensor, to determine a type ofstick electrode employed based at least in part on transients of theelectrical parameter relative to a threshold, and to increase an enginespeed of an engine of the welding power supply unit to an elevated levelor maintain the engine speed at an initial level, lower than theelevated level, based at least in part upon the type of the stickelectrode employed.
 14. The welding system of claim 13, wherein theelectrical parameter is voltage of the welding power.
 15. The weldingsystem of claim 13, wherein the electrical parameter is current of thewelding power.
 16. The welding system of claim 13, wherein the controlcircuitry is configured to control an engine speed of the welding powersupply unit based at least in part upon the type of the stick electrodeemployed.
 17. The welding system of claim 16, wherein the controlcircuitry causes the engine speed to increase to the elevated level ifthe determined type of the stick electrode employed is a cellulose orXX10 electrode.
 18. The welding system of claim 17, wherein the stickelectrode employed is determined to be a cellulose or XX10 electrode ifa predetermined voltage profile is detected within a predetermined timeafter initiation of the welding arc.
 19. The welding method of claim 1,comprising comparing voltage events of the voltage monitored to athreshold to determine if the voltage events represent use of acellulose electrode.
 20. The welding method of claim 6, comprisingcomparing voltage events of voltage monitored to a threshold todetermine if the voltage events represent use of a cellulose electrode.